This core has three goals. The first is to provide expert and uniform in vivo evaluation of the compounds that are judged worthy of evaluation from in vitro testing. This core will also provide all of the normal tissue toxicology testing. All the tumor testing will be performed with the HT29/Ak human tumor transplanted into nu/nu mice. The normal tissue toxicology testing will be performed with the nu/nu mice beating the HT29 tumor (because of the possibility of active drug "leaking" into the vasculature from the tumor), and with CD1 mice (without tumors). The second goal of the project is to provide a centralized cell line, medium and serum bank to each project to ensure uniformity as much as possible between the test systems used by all of the projects. The Core will also perform the serum testing and mycoplasma testing of the cell lines used by all the projects. The third goal is to provide statistical and database support for all of the projects in the Program Project.